Labracinus atrofasciatus ( Herre, 1933 )

Gill, Anthony C., Sorgon, Kent Elson S., Brun, Victor & Tea, Yi-Kai, 2021, New records and redescription of Labracinus atrofasciatus (Herre, 1933) (Teleostei: Pseudochromidae), Raffles Bulletin of Zoology 69, pp. 438-447 : 439-445

Labracinus atrofasciatus ( Herre, 1933)

Black-barred dottyback ( Figs. 1–3 , 4A, 5; Tables 1, 2)

Dampieria atrofasciatus Herre, 1933: 17 (type locality: Culion, Philippines); 1934: 47 (list); 1953: 370 (list); Roxas & Martin, 1937: 123 (list); Böhlke, 1953: 69 (list).

Labracinus atrofasciatus – Schultz, 1967: 40, fig. 8 (description); Gill, 1999: 2561 (key); 2004: 24, figs. 12, 13 (redescription); Allen et al., 2003: 273 (colour photograph); Allen & Erdmann, 2012: vol. 1, 324 (colour photograph).

Material examined. CAS SU 25518, 105.5 mm SL (holotype), Culion, Culion Island , Calamian Group, Philippine Islands, A.W. Herre, April 1931 .

AMS I.49470-001 (GenBank MZ 753670 ), 134.4 mm SL, fishery landing site in Barangay Sandoval , Municipality of Taytay, northern Palawan, Philippines, 11°06′38″N, 119°32′24″E, V. Brun, 30 November 2019 . — PNM 15645 (GenBank MZ 753671 ), 146.5 mm SL, collected with AMS I.49470-001. — PNM 15646 (GenBank MZ 753672 ), 142.0 mm SL, same data as AMS I.49470-001, except collected 5 January 2020 .

Diagnosis. Labracinus atrofasciatus differs from congeners in having a series of narrow, dark blue to black oblique bars on the body. It also differs in having relatively high numbers of horizontal scale rows above the anal-fin origin (24–27 + 1 + 4–5 = 30–33), pseudobranch filaments (22–24), and circumpeduncular scales (30–32).

Description (data first for the holotype, followed where different by minimum and maximum values for non-types in parentheses). Dorsal-fin rays II,25, all segmented rays branched; anal-fin rays III,14, all segmented rays branched; pectoral-fin rays 20/20 (19–20); upper procurrent caudal-fin rays 6; lower procurrent caudal-fin rays 5; total caudal-fin rays 28; scales in lateral series 60/60 (58–62); anterior lateral-line scales 53/51 (47–53); anterior lateral line terminating beneath segmented dorsal-fin ray 19/19 (17–21); posterior lateral-line scales 18 +?/19 + 2 (19–21 + 2); scales between lateral lines 7/7 (6–8); horizontal scale rows above anal-fin origin 24 + 1 + 5/25 + 1 + 5 (24–27 + 1 + 4–5 = 30–33); circumpeduncular scales 32 (30–32); predorsal scales 34 (31–38); scales behind eye 2 (3–4); scales to preopercular angle 9 (9–11); gill rakers 6 + 14/7 + 13 (5–6 + 13–14 = 18–20); pseudobranch filaments 23/24 (22–23).

Lower lip complete; dorsal and anal fins with well-developed scale sheaths; predorsal scales extending anteriorly to mid AIO pores (mid AIO to posterior nasal pores); opercle relatively smooth, without distinct serrations; teeth of outer ceratobranchial-1 gill rakers with well-developed teeth running most of length of upper rakers, these becoming restricted to distal halves and raker tips of lower rakers; anterior dorsal-fin pterygiophore formula S/S/S + 3/1 + 1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1 + 1 (S/S/S + 3/1 + 1/1/1/1/1/1/1/1/1/1/1/1/1/1/1/1 + 1); dorsal-fin spines slender, tips flexible; anal-fin pterygiophore formula 3/1 + 1/1/1/1/1/1/1 + 1/1/1 + 1/ 1 + 1 (3/1 + 1/1/1/1/1/1/1 + 1/1/1 + 1/ 1 + 1 or 3/1 + 1/1/1/1/1/1 + 1/1/1/1 + 1/ 1 + 1); anal-fin spines relatively stout and pungent, second spine slightly stouter than third; pelvic-fin spine slender, tip weakly pungent; second segmented pelvic-fin ray longest or equal to third (second or third ray longest); caudal fin rounded; vertebrae 11 + 17; epineurals 14 (12–14); epurals 3 ( Fig. 3 ).

Upper jaw with 2 (1–2) pairs of curved, enlarged caniniform teeth anteriorly, and about 5 (at symphysis) to 1–2 (on sides of jaw) irregular rows of small conical teeth, outermost of rows of teeth much larger and more curved than those of inner rows; lower jaw with 2 (1) pairs of curved, enlarged caniniform teeth anteriorly, and about 3 (at symphysis) to 1 (on sides of jaw) inner rows of small conical to caniniform teeth, those on middle of jaw enlarged and caniniform; vomer with 1–2 rows of small conical teeth arranged in chevron; palatine with 1 row of small conical teeth, more or less contiguous anteriorly with posterolateral arm of vomerine tooth patch; ectopterygoid edentate; tongue moderately pointed and edentate. Morphometric data are summarised in Table 2.

Live colouration. Based on specimens from Taytay, Palawan ( Figs. 1 , 2 ): head grey-brown to olive, paler ventrally, becoming brownish red behind eye and on upper part of cheek; scales on upper part of head each with blue to dark olive spot; dark blue curved mark extending around posterior rim of orbit to middle of upper lip, mark broadest behind eye, becoming indistinct ventrally and anteriorly; blue curved mark narrowly bordered ventrally with bright red; iris red to orange-yellow with blue sub-oval ring around pupil; anterior body, nape, and dorsal part of body grey-brown to olive, becoming paler and more yellowish on breast and near pectoral-fin base, each scale within grey-brown to olive region with basal blue to dark olive spot; remainder of body olive-pink to bright orange-red, sometimes abruptly paler on caudal peduncle, with about 9–15 narrow to broad dark blueblack bars extending from anterior lateral line or dorsal-fin base to ventral part of body, these variously anastomosing dorsally; caudal peduncle sometimes pale, with narrow dark blue-black bars or intermittent streaks; dorsal fin olive-grey, becoming red basally behind middle part of fin, the red area gradually expanding posteriorly to full length of terminal few rays; distal margin of anterior part of fin narrowly bright blue; dorsal fin with fine blue spots, these aligning to form curved marks on red part of fin, and to form short streaks distally on grey part of fin; anal fin pinkish grey to bright red with narrow bright blue distal margin; caudal fin pinkish olive to orange-red or crimson; pectoral fins greyish to yellowish hyaline, with dark grey mark on axil and base of fin; pelvic fins olive-yellow with pinkish-grey rays. See Comparative notes below for live colouration of females.

200 km 200 km

Fig. 4. Map of the Philippines, showing distribution records for selected species of pseudochromids endemic to the Calamian Islands and Palawan regions. A, Labracinus atrofasciatus , photograph of PNM 15645; B, Pseudochromis colei , photograph of aquarium specimen (not retained); C, P. eichleri , photograph of AMS I.45651-001 (paratype); D, Manonichthys scintilla , photograph of USNM 382744 (paratype). Photographs by V. Brun (A), Y. K. Tea (B), G. R. Allen (C), and J. T. Williams (D).

Preserved colouration. Similar to live colouration; greybrown to olive areas on head, body, and fins become brown; blue to dark olive spots on head and body scales become dark brown; red areas on body and fins become tan; dark blueblack bars and streaks on body and caudal peduncle become dark grey-brown; blue spots on fins become dark brown.

Etymology. The specific epithet is derived from the Latin ‘atrum’, black, and ‘fascia’, band, in reference to the striking markings on the body of this species. Labracinus atrofasciatus is known locally as ‘akot’ in Cuyonon, a language spoken mostly in Cuyo Islands and coastal areas of Palawan in the Philippines, where it shares the local name with the congeneric L. cyclophthalmus .

Habitat and distribution. We extend the known distribution of L. atrofasciatus from Culion in the Calamian Islands southward to Taytay , Palawan (Fig. 4A). Herre (1933) did not include habitat details for the holotype, and we also lack details for the Taytay specimens. However, Allen (pers. comm. to ACG, 2020) provided the following details for his Lajo and Tangat Island observations :

“1. Lajo Island, 11°59.19′N, 119°57.64′E: area with freshwater runoff due to a spring at the shoreline; limestone reef development about 50 m from shore; patchy mangroves along shore with some Enhalus seagrass in shallows; L. atrofasciatus (about 10 individuals) seen on the shallow flat between the reef and shore, consisting of sand, rubble, and patches of dead coral. Photo taken here ( Fig. 5A ).”

“2. Tangat Island, 11°57.59′N, 120°03.56′E: fringing reef on edge of steep, high cliffs forming south-western Tangat Island, fringing reef about 20 m in width before dropping steeply to 20 m depth. One individual seen.”

Comparative notes. Gill (2004) recognised three species of Labracinus in his revision of the Pseudochrominae : L. atrofasciatus and L. cyclophthalmus ( Müller & Troschel, 1849) from throughout the West Pacific ( Japan to northwest Australia and east to Papua New Guinea), and L. lineatus (Castelnau, 1875) from Western Australia. However, White et al. (2013) recognised two species from Indonesian waters based on apparent differences in live colouration (and also in COI barcode sequences; W. T. White pers. comm. to ACG), and Ito et al. (2021) recognised L. ocelliferus ( Fowler, 1946) as a valid species based on morphological and colouration characters, as well as differences in 12S ribosomal RNA sequences. In spite of the recognition of L. ocelliferus (considered a synonym of L. cyclophthalmus by Gill, 2004), the likelihood that L. cyclophthalmus is a complex of similar species, and the new information on variation in L. atrofasciatus , the characters provided by Gill (2004) still mostly hold as diagnostic for L. atrofasciatus : relatively high number of horizontal scale rows above the anal-fin origin (24–27 + 1 + 4–5 = 30–33 versus 16–25 + 1 + 3–6 = 21–30, usually 17–23 + 1 + 3–5 = 21–28 in the other species); relatively high number of pseudobranch filaments (22–24 versus 12–20); relatively high number of circumpeduncular scales (30–32 versus 24–30); and presence of dark blue to black oblique bars on the sides of the body. An exception is the presence of a large (subequal to pupil) black spot on the posterior part of the dorsal fin. This marking is obvious in the holotype ( Fig. 5B ) and also apparent in Allen et al. (2003) and Allen & Erdmann’s (2012) photograph of the individual from Lajo Island ( Fig. 5A ). It is absent, however, in each of the Taytay specimens.

Dorsal fin colouration appears to be sexually dimorphic in Labracinus species ( Schultz, 1967; Gill, 2004). Other aspects of the dorsal fin colouration of the holotype and individual photographed from Lajo Island suggest that they are females, whereas the specimens from Taytay, Palawan, appear to be males. Aside from the presence of a posterior dorsal-fin spot, the presumed female photographed from Lajo Island differs in having an olive-brown body with a translucent yellow caudal fin. Both sexes appear to have a pale cream caudal peduncle (more abruptly so in the putative female than males) and oblique black bars on the body (more prominent in the males). However, given the paucity of specimens in museums, possibility of ontogenetic colouration differences, and poorly documented nature of this species, further study with additional fresh material of both sexes is needed to corroborate these differences.

Comparisons of mitochondrial COI sequences of L. atrofasciatus with other publicly available pseudochromid sequences recovers L. cyclophthalmus as its closest relative (14.2–15.7% uncorrected pairwise distance). We note however that several comparative sequences included in the above analysis retrieved from GenBank appear to be erroneous. These include two sequences of Pseudochromis jamesi ( MW630777 and KT883614 ), and one of Labracinus lineatus ( KU943558 ), all three of which are most likely misidentifications of L. cyclophthalmus . We provisionally recognise Labracinus sp. 1 and sp. 2 from Indonesia ( JN312221 and GU674050 ) as L. cyclophthalmus , pending further research concerning the taxonomy of L. cyclophthalmus . Until more appropriate sequences of related species are made available (including the Western Australian L. lineatus ), we refrain from putting emphasis on Labracinus relationships. Nonetheless, we take the opportunity to include new, previously unavailable mitochondrial COI sequences of L. atrofasciatus .

Remarks. One of the Taytay specimens (PNM 15646) exhibits two unusual osteological features: the first caudal vertebra (12th vertebra) possesses a haemal spine and paired parapophyses (versus a haemal spine and no parapophyses), and the second last vertebra (pu2) has an elongate neural spine (versus short neural spine). We are not aware of similar modification of the first caudal vertebra in pseudochromids, although similar morphology occurs in some anthiadine fishes ( Baldwin, 1990; Pogonoski & Gill, 2021). Variation in the length of the pu2 neural spine in pseudochromids was reviewed by Gill (2013), and is known in two genera: Anisochromis Smith, 1954 , and Assiculoides Gill & Hutchins, 1997 .

Figures

Fig. 1. Two specimens of Labracinus atrofasciatus (approximately 150 and 190 mm TL) amongst catch of other reef fishes at a fish landing site in Barangay Sandoval, Municipality of Taytay, northern Palawan, Philippines. Specimens not retained. Photograph by V. Brun.

Fig. 2. Freshly dead Labracinus atrofasciatus specimens from Macuao Island, northern Palawan, Philippines. A, PNM 15645, 146.5 mm SL; B, PNM 15646, 142.0 mm SL; C, AMS I.49470-001, 134.4 mm SL. Photographs by V. Brun (A) and K. E. S. Sorgon (B, C).

Fig. 3. X-radiographs of Labracinus atrofasciatus. A, CAS-SU 25518, 105.5 mm SL holotype (via Smithsonian Division of Fishes); B, PNM 15645, 146.5 mm SL; C, PNM 15646, 142.0 mm SL; D, AMS I.49470-001, 134.4 mm SL. Radiographs by K. Parkinson (B–D).

Fig. 5. A, putative female of Labracinus atrofasciatus, in situ photograph taken in Lajo Island, Palawan, Philippines; B, holotype of L. atrofasciatus, CAS-SU 25518, 105.5 mm SL holotype (image adapted from Gill, 2004). Note the posterior dorsal-fin spot and faint vertical bars in both specimens. Photographs by G. R. Allen & M. V. Erdmann (A) and P. Crabb (B).